Lake Geneva weather in September: Lake Geneva, Wisconsin: normal highs, lows, rain and records for September
Lake Geneva in September has a normal high of 76°F and a normal low of 54°F, a daily mean of 65°F, falling from 81°F on the 1st to 70°F by the 30th. Measurable precipitation falls on 10 days in a normal September, 3.65 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 25°C and low of 12°C, 93 mm of precipitation in September.
- NOAA stationLake Geneva Wastewater Treatment Plant
- Station IDUSC00474457
- Location42.60°N 88.43°W
- Elevation846 ft (258 m)
- Population8,691
- Jan 30° 15°
- Feb 35° 17°
- Mar 45° 26°
- Apr 59° 37°
- May 72° 48°
- Jun 81° 58°
- Jul 86° 63°
- Aug 83° 61°
- Sep 76° 54°
- Oct 63° 42°
- Nov 47° 31°
- Dec 35° 21°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Lake Geneva in September?
The normal high is 76°F and the normal low 54°F, for a daily mean of 65.1°F. September is 7.2°F cooler than August and 12.7°F warmer than October. September is the 4th warmest month of the year in Lake Geneva and the 4th wettest. Across the month the normal high falls 11°F, from 81°F on September 1 to 70°F on September 30. From one year to the next September's mean temperature typically moves about 3.2°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 62°F and 68°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 33%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 81°F | 59°F | 31% | 19% |
| September 8 | 79°F | 57°F | 31% | 20% |
| September 15 | 77°F | 54°F | 32% | 20% |
| September 22 | 74°F | 51°F | 33% | 21% |
| September 30 | 70°F | 48°F | 33% | 21% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 81°F | 59°F | 31% | 19% | 13 h 10 min |
| September 2 | 81°F | 59°F | 31% | 19% | 13 h 10 min |
| September 3 | 81°F | 58°F | 31% | 19% | 13 h 10 min |
| September 4 | 81°F | 58°F | 31% | 19% | 13 h |
| September 5 | 80°F | 58°F | 31% | 19% | 13 h |
| September 6 | 80°F | 57°F | 31% | 19% | 13 h |
| September 7 | 80°F | 57°F | 31% | 19% | 13 h |
| September 8 | 79°F | 57°F | 31% | 20% | 12 h 50 min |
| September 9 | 79°F | 56°F | 32% | 20% | 12 h 50 min |
| September 10 | 79°F | 56°F | 32% | 20% | 12 h 50 min |
| September 11 | 78°F | 56°F | 32% | 20% | 12 h 50 min |
| September 12 | 78°F | 55°F | 32% | 20% | 12 h 40 min |
| September 13 | 78°F | 55°F | 32% | 20% | 12 h 40 min |
| September 14 | 77°F | 55°F | 32% | 20% | 12 h 40 min |
| September 15 | 77°F | 54°F | 32% | 20% | 12 h 30 min |
| September 16 | 76°F | 54°F | 32% | 21% | 12 h 30 min |
| September 17 | 76°F | 53°F | 33% | 21% | 12 h 30 min |
| September 18 | 76°F | 53°F | 33% | 21% | 12 h 30 min |
| September 19 | 75°F | 53°F | 33% | 21% | 12 h 20 min |
| September 20 | 75°F | 52°F | 33% | 21% | 12 h 20 min |
| September 21 | 74°F | 52°F | 33% | 21% | 12 h 20 min |
| September 22 | 74°F | 51°F | 33% | 21% | 12 h 10 min |
| September 23 | 73°F | 51°F | 33% | 21% | 12 h 10 min |
| September 24 | 73°F | 51°F | 33% | 21% | 12 h 10 min |
| September 25 | 73°F | 50°F | 33% | 21% | 12 h 10 min |
| September 26 | 72°F | 50°F | 33% | 21% | 12 h |
| September 27 | 72°F | 49°F | 33% | 21% | 12 h |
| September 28 | 71°F | 49°F | 33% | 21% | 12 h |
| September 29 | 71°F | 48°F | 33% | 21% | 11 h 50 min |
| September 30 | 70°F | 48°F | 33% | 21% | 11 h 50 min |
- Normal high
- 76°FSeptember average
- Normal low
- 54°FSeptember average
- Precipitation
- 3.65 inmonth total
- Days with precipitation
- 100.01 inch or more
- Days at 90°F or more
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 21
- Days at 80°F or more
- 11
- Sunshine
- 78%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USC00474457; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Lake Geneva in September?
On a given September day the chance of 0.01 inch or more is 32% on average, highest around September 27 (33%). In all, 3.65 in falls on 10 days of a normal September, 1 of them with an inch or more.
In a normal September in Lake Geneva, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USC00474457.
What are the records for September in Lake Geneva?
The warmest September temperature on this station's record (since 1945) is 100°F, on September 1, 1953; the coldest is 28°F, on September 30, 1993. The wettest September brought 12.25 in (1970).
The September mean against the 1991-2020 normal of 65.1°F: 2023 64.6°F (−0.5), 2024 64.8°F (−0.3), 2025 64.2°F (−0.9), 2026 65.0°F (−0.1). 0 of 4 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2023 | 64.6°F | −0.5°F | 4.62 in |
| 2024 | 64.8°F | −0.3°F | 1.90 in |
| 2025 | 64.2°F | −0.9°F | 2.39 in |
| 2026 | 65.0°F | −0.1°F | 5.19 in |
Source: records: ACIS, station USC00474457; recent months: ACIS, station USC00474457. Records and recent months use complete months only.
How does September in Lake Geneva compare across Wisconsin?
Across the 165 places PlainClimate covers in Wisconsin, September normal highs run from 64°F in Laona to 77°F in West Allis; Lake Geneva's is 76°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Lake Geneva in August83°F by day, 61°F at night
- Lake Geneva in October63°F by day, 42°F at night
- Lake Geneva through the yearEvery month, frost dates, records and recent years
- Wisconsin in SeptemberThe statewide normal and the warmest and coolest places
- West Allis: Wisconsin's warmest Septembernormal high 77°F